scholarly journals Evolution of the electronic structure in open-shell donor-acceptor organic semiconductors

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Zhongxin Chen ◽  
Wenqiang Li ◽  
Md Abdus Sabuj ◽  
Yuan Li ◽  
Weiya Zhu ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Organic Semiconductors ◽  
High Performance ◽  
Closed Shell ◽  
Open Shell ◽  
Ground State Structure ◽  
Structure Property ◽  
System A ◽  
Diradical Character ◽  
Donor Acceptor

AbstractMost organic semiconductors have closed-shell electronic structures, however, studies have revealed open-shell character emanating from design paradigms such as narrowing the bandgap and controlling the quinoidal-aromatic resonance of the π-system. A fundamental challenge is understanding and identifying the molecular and electronic basis for the transition from a closed- to open-shell electronic structure and connecting the physicochemical properties with (opto)electronic functionality. Here, we report donor-acceptor organic semiconductors comprised of diketopyrrolopyrrole and naphthobisthiadiazole acceptors and various electron-rich donors commonly utilized in constructing high-performance organic semiconductors. Nuclear magnetic resonance, electron spin resonance, magnetic susceptibility measurements, single-crystal X-ray studies, and computational investigations connect the bandgap, π-extension, structural, and electronic features with the emergence of various degrees of diradical character. This work systematically demonstrates the widespread diradical character in the classical donor-acceptor organic semiconductors and provides distinctive insights into their ground state structure-property relationship.

scholarly journals A new family of [IrCl5(NO)]-salts. Structural diversity tuned by aryl embraces

2014 ◽  
Vol 70 (a1) ◽  
pp. C649-C649
Author(s):  
Florencia Di Salvo ◽  
Ana Foi ◽  
Ricardo Baggio ◽  
Damian Bikiel ◽  
Fabio Doctorovich
Keyword(s):  
Electronic Structure ◽  
Structural Diversity ◽  
Closed Shell ◽  
Open Shell ◽  
Phosphonium Salts ◽  
Structural Behaviour ◽  
Interaction Domain ◽  
Theoretical Evaluation ◽  
New Family ◽  
Electronic Distribution

The interactions experimented by multiple phenyl or other aromatic groups in crystals have been described as ``embraces'' since 1995, when Dance and co-workers developed the embrace paradigm as an important and widespread tool of supramolecular chemistry. There are three main classes of Multiple Phenyl Embraces (MPE) depending on the total number of phenyl rings (Ph) located in the interaction domain: sextuple (6PE), quadruple (4PE), and double phenyl embrace (2PE) [1]. Recently, an accurate theoretical evaluation of the MPE motifs between PPh4+was presented by Novoa et al [2]. In our laboratory we demonstrated that by changing the counterion of the [IrCl5(NO)]-salts from K+to PPh4+, it was possible to stabilize an excited state of the metal complex anion. The electronic distribution of the IrNO moiety in K[IrCl5(NO)] can be depicted as the closed-shell electronic structure IrIII–NO+. However, in PPh4[IrCl5(NO)] an unprecedented electronic perturbation takes place favouring the open-shell electronic structure IrIv–NO* [3]. These results together with the interesting systematic studies on MPE, encouraged us to explore the synthesis of new phosphonium salts. In this work we report new phosphonium ions of the type Ph3PR+and five new Ph3PR[IrCl5(NO)] salts (R = aryl, methylaryl). Structural analyses of these compounds were done in the context of the multiple embraces motifs. For the new unsymmetrical [IrCl5(NO)]-salts, the supramolecular arrangements are different from the one observed for the PPh4+one. In the last one, the 4PE infinite chains run parallel to the columns described by the anions [3] and for the others, the presence of bulkier substituents give place to symmetries that favours other kinds of aryl embraces resulting in a side by side location of the anions. Finally, DFT calculations were performed to evaluate the theoretical concerns regarding the structural behaviour, as well as the electronic distribution along the family of compounds.

scholarly journals Constructing Donor-Resonance-Donor Molecules for Acceptor-Free Bipolar Organic Semiconductors

Research ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
He Jiang ◽  
Jibiao Jin ◽  
Zijie Wang ◽  
Wuji Wang ◽  
Runfeng Chen ◽  
...  
Keyword(s):  
Organic Semiconductors ◽  
High Performance ◽  
Molecular Design ◽  
Stimuli Responsive ◽  
Light Emitting ◽  
Deep Blue ◽  
Device Structures ◽  
Device Applications ◽  
Donor Acceptor ◽  
Organic Optoelectronic

Organic semiconductors with bipolar transporting character are highly attractive as they offer the possibility to achieve high optoelectronic performance in simple device structures. However, the continual efforts in preparing bipolar materials are focusing on donor-acceptor (D-A) architectures by introducing both electron-donating and electron-withdrawing units into one molecule in static molecular design principles. Here, we report a dynamic approach to construct bipolar materials using only electron-donating carbazoles connected by N-P=X resonance linkages in a donor-resonance-donor (D-r-D) structure. By facilitating the stimuli-responsive resonance variation, these D-r-D molecules exhibit extraordinary bipolar properties by positively charging one donor of carbazole in enantiotropic N+=P-X- canonical forms for electron transport without the involvement of any acceptors. With thus realized efficient and balanced charge transport, blue and deep-blue phosphorescent organic light emitting diodes hosted by these D-r-D molecules show high external quantum efficiencies up to 16.2% and 18.3% in vacuum-deposited and spin-coated devices, respectively. These results via the D-r-D molecular design strategy represent an important concept advance in constructing bipolar organic optoelectronic semiconductors dynamically for high-performance device applications.

scholarly journals Stable dinitrile end-capped closed-shell non-quinodimethane as donor, acceptor and additive of organic solar cells

2021 ◽  
Author(s):  
Liang weixuan ◽  
Liu Peng ◽  
Zhang Yiheng ◽  
Zhu weiya ◽  
Tao Xinyang ◽  
...  
Keyword(s):  
Solar Cells ◽  
Organic Solar Cells ◽  
Closed Shell ◽  
Open Shell ◽  
Donor Acceptor ◽  
Moderate Energy ◽  
Shell Chemical ◽  
New Perspective ◽  
Enhanced Photostability ◽  
Photovoltaic Material

Non-fullerene acceptors exhibit great potential to improve photovoltaic performances of organic solar cells. However, it is important to further enhance chemical stability and device durability for future commercialization, especially for Y6-series small molecule acceptors with 2-(3-oxo-2,3-dihydroinden-1-ylidene)malononitrile (IC) type as ending group. In this work, an IC-free photovoltaic material YF-CN consisting of 2-fluoren-9-ylidenepropanedinitrile terminal was designed and synthesized by stille coupling. YF-CN exhibited closed-shell chemical structure with enhanced photostability and improved morphological compatibility with the binary PCE10:Y6 blend. The moderate energy level makes YF-CN could serve as a multifunctional material, such as donor, acceptor and the third component. When adding YF-CN as second donor into PCE10:Y6 system, an improved power conversion efficiency of 12.03% was achieved for as-cast device. Importantly, the ternary PCE10:YF-CN:Y6-devices showed enhanced storage durability maintaining 91% of initial PCE after the 360 hours. This work provides new perspective to understand the open-shell character of donor and closed-shell structure of acceptors, respectively, as well as promising design concept of stable IC-free acceptors for organic solar cells.

Reactivities of singlet oxygen: open-shell or closed-shell?

2020 ◽  
Vol 22 (24) ◽  
pp. 13373-13377
Author(s):  
Zexing Qu
Keyword(s):  
Electronic Structure ◽  
Singlet Oxygen ◽  
Closed Shell ◽  
Open Shell

The electronic structure and the reactivity of singlet oxygen with respect to two typical reactions.

scholarly journals Structure and Doping Optimization of IDT-Based Copolymers for Thermoelectrics

Polymers ◽  
2020 ◽  
Vol 12 (7) ◽  
pp. 1463
Author(s):  
Tongchao Liu ◽  
Dexun Xie ◽  
Jinjia Xu ◽  
Chengjun Pan
Keyword(s):  
Organic Semiconductors ◽  
Carrier Mobility ◽  
Carrier Transport ◽  
Room Temperature ◽  
Charge Carrier Transport ◽  
Structure Property ◽  
Polymer Backbone ◽  
Donor Acceptor ◽  
Higher Carrier Mobility ◽  
The Relationship

π-conjugated backbones play a fundamental role in determining the thermoelectric (TE) properties of organic semiconductors. Understanding the relationship between the structure–property–function can help us screen valuable materials. In this study, we designed and synthesized a series of conjugated copolymers (P1, P2, and P3) based on an indacenodithiophene (IDT) building block. A copolymer (P3) with an alternating donor–acceptor (D-A) structure exhibits a narrower band gap and higher carrier mobility, which may be due to the D-A structure that helps reduce the charge carrier transport obstacles. In the end, its power factor reaches 4.91 μW m−1 K−2 at room temperature after doping, which is superior to those of non-D-A IDT-based copolymers (P1 and P2). These results indicate that moderate adjustment of the polymer backbone is an effective way to improve the TE properties of copolymers.

Balancing DFT Interaction Energies in Charged Dimers Precursors to Organic Semiconductors

2019 ◽  
Author(s):  
Alberto Fabrizio ◽  
Riccardo Petraglia ◽  
Clemence Corminboeuf
Keyword(s):  
Organic Semiconductors ◽  
Density Functional ◽  
Radical Cations ◽  
Closed Shell ◽  
Open Shell ◽  
Binding Energies ◽  
Interaction Energies ◽  
Functional Theory ◽  
Energy Profiles ◽  
London Dispersion

Accurately describing intermolecular interactions within the framework of Kohn-Sham density functional theory (KS-DFT) has resulted in numerous benchmark databases over the past two decades. By far, the largest efforts have been spent on closed-shell, neutral dimers for which today, the interaction energies and geometries can be accurately reproduced by various combinations of dispersion-corrected density functional approximations (DFAs). In sharp contrast, charged, open-shell dimers remain a challenge as illustrated by the analysis of the OREL26rad benchmark set consisting of pi-dimer radical cations. Aside from the methodological aspect, achieving a proper description of radical cationic complexes is appealing due to their role as models for charge carriers in organic semiconductors. In the interest of providing an assessment of more realistic dimer systems, we construct a dataset of large radical cationic dimers (CryOrel) and jointly train the 19 parameters of a dispersion corrected, range-separated hybrid density functional (wB97X-dDsC), with the objective of providing the maximum balance between the treatment of long-range London dispersion and reduction of the delocalization error. These conditions are essential to obtain accurate energy profiles and binding energies of charged, open-shell dimers. Comparisons with the performance of the parent wB97X functional series and state-of-the-art wavefunction based methods are provided. <br>

scholarly journals Rates and energetics of intramolecular electron transfer processes in conjugated metallofullerenes

2013 ◽  
Vol 371 (1998) ◽  
pp. 20120490 ◽  
Author(s):  
Christina Schubert ◽  
Marc Rudolf ◽  
Dirk M. Guldi ◽  
Yuta Takano ◽  
Naomi Mizorogi ◽  
...  
Keyword(s):  
Closed Shell ◽  
Open Shell ◽  
Ion Pair ◽  
Intramolecular Electron Transfer ◽  
Redox Potentials ◽  
Endohedral Metallofullerenes ◽  
Transfer Processes ◽  
Donor Acceptor ◽  
Electron Transfer Processes ◽  
Pair State

In this paper, we report on the design, redox potentials, excited state energies and radical ion pair state energies in electron donor–acceptor conjugates comprising the electron-donating π -extended tetrathia- fulvalene and several electron-accepting fullerenes. To this end, we contrast an empty fullerene, that is, C 60 , with two endohedral metallofullerenes, that is, open-shell La@C 82 and closed-shell La 2 @C 80 , in terms of charge separation and charge recombination dynamics.

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